This invention relates to a tube connector comprising an elongate hollow body with an opening at both ends for receiving the end of a tube of a pair of tubes to be coupled to each other.
Such a tube connector is known, for use in electricity conduits, from CH-A-682.691.
It is also known to install telecommunication cables, in particular glass fiber cables, in ducts laid underground, by blowing in combination with pushing. Besides telecommunication cables, flexible glass fiber bundles can be installed in subducts by means of blowing. These techniques have been respectively described in; for instance, E-P-A-0.292.037 and EP-A-0.108.590.
If by means of an installation unit a glass fiber cable or bundle is to be installed over several tube sections, it is known to connect such tube sections by means of tube connectors suitable therefor. Such a tube connector is described, for instance, in EP-A-0.349.344. This known connector comprises a hollow cylindrical body and is provided on opposite sides with means in the form of a clamping ring and an O-ring to realize an airtight coupling between the tube sections, in order that no air pressure that is being used for the purpose of blowing is lost through leakage at the coupling.
A drawback of the known connector is that it is rather costly and that it has a rather large external diameter relative to the external diameter of the tubes to be connected. This can be objectionable if in a small space, for instance when installing several tube sections in a larger surrounding duct, many couplings are to be arranged in one place and also when coupled tubes are to be manipulated, in particular when this is to be done in a limited space, because then an unduly large connector can get stuck.
A problem in installing glass fiber cables and fiber bundles is, generally, that due to the non-linear pressure gradient prevailing in the tube the blowing force that is exerted on the cable or bundle in the initial portion of the tube is smaller by about a factor of 2 than if the pressure gradient were linear. As a consequence, the length of cable that can be installed is reduced by about a factor of two. In the case of glass fiber cables this problem can be solved by exerting supplemental pushing forces on the cable, as has been described in EP-A-0.292.037. In the case of flexible fiber bundles, however, this is not possible because these exhibit a phenomenon known by the name of "buckling".